[Stalker]

You cant go by what they publish thats for sure.

My Sniper 370 has always produced the up to speeds with a 370gnish arrow. I guess I got lucky. 350 fps with a 425gn.

They list that the Patriot/Amped 425 shoots up to 425 fps with 160lbs of KE. For it to have 160lbs of KE it must be shooting a 400gn arrow at 425 fps which is false. Very similar specs published for the Wrath as well.

I haven't shot the supplied 400gn arrow that came with my Amped 425. It does shoot a 450gn arrow at 382fps. A 435gn 387-389fps. I'm guessing around 400fps with the 400gn. I may run a 400gn through the chrono just to see. I wont do a 370gn though. But suspect thats where the 425fps was supposed to come from.

I'll also add published draw weights differ. Some say 195lbs for the 425's and some say 200lbs

Specifications

Velocity	Up to 425 fps
Kinetic Energy	160 ft-lbs
Width (axle-to-axle) Cocked	12" AXLE - AXLE
Width (axle-to-axle) Uncocked	15.75" AXLE - AXLE
Draw Weight	200 lbs
Power Stroke	14.50 in
Weight	7.8 lbs
Product Length	35.8 in
String Length	35.11 in
Overall Length	35.8 in
SKU	C0005

Reviews

 

[Stalker]

Over the years crossbow manufactures probably had complaints something like "my buddy and I have the same
make and series of crossbows, shooting the same arrow point weight combination but one crossbow is shooting
faster than the other". They could have got together to use the same chronograph, shoot through the same area
and use the same arrow-point weight. So to prevent conflict, they changed their advertisement to "up to" in regards
to speed.
I personally have experience with the same brand and series of crossbows shooting different speeds when both
were tuned identical. Cams in the same position and same axle to axle measurements.

Here are some things that can cause differences in speed in feet per second from one crossbow to the other.
1)different limb deflections, 2)bowstring and or cables serving tighter on one which makes that area stiffer.
3)a bearing with more grease makes for a tighter fit. Axle holes in the bearing or bushing not properly manufactured,
over size or too snug. 4)more downward pressure on the bow string and or arrow retainer causing more friction.

In order to have both crossbows shooting the same speed, advance the cams in the slow one or back the cams off
in the faster one. The crossbows will both be in time but the cams will be in a different position from one crossbow
to the other. The axle to axle measurements can differ but this is just a guide line.

Another example I found with two crossbows of the same brand and series. The riser from one would inter change
with either rail-stock. However the other riser would only fit it's own original rail-stock. There was a difference in
machining causing this.

Wishing you all the best.
Take care.

Yes lots of variables bow to bow. Limb dampener position string weight etc. Plus all that you mentioned.

If you use a archery calculator like this one. Kinetic Energy and Momentum Calculator You will see a 370gn arrow at 425fps is a lot closer to real world KE and momentum. Where as the 400gn at 425 fps is 160lbs of KE. Which is not even close.

I just ran a 400gn arrow through my chrono and guessed right above. It shot 400fps no where near 160lbs of KE.

Imo they calculate the speeds of the 425's with a 370gn arrow. But calculated the KE with a 400gn by mistake would be my guess and 370gn speeds of 425 fps. They can't have it both ways!

 

[Stalker]

The Excalibur and the Sniper seam close to me. I'm getting 382fps with a 450 gn out of my Amped. And 400fps with a 400gn.

So I'm not seeing 397 with a 455gn.

I'll also add my cams seem pretty far advanced and my ata is dead on at 15.75"

Bring them down sometime and shoot them through my chrono.